Rename DataObject method name

[sabina-talipova]

Issue

• DEP PHP Support in CMS5 silverstripe-userforms#1182

[emteknetnz]

We should not be renaming this method because of the failure on a totally unrelated module - that won't stop the same issue happening again on a different module

Instead we should be using is_callable() as mentioned here

[sabina-talipova]

Instead we should be using is_callable() as mentioned here

Using this approach, some "setProperty" methods in another classes fail Unit tests. Initially I implemented this approach, but after testing I think better to rename method and open issue to fix problem with private methods.
Please have a look: 31df80e
and
https://github.com/silverstripe/silverstripe-framework/actions/runs/3879244028/jobs/6616354722

[emteknetnz]

In ViewableData::__set() it should be is_callable([$this, $method]), not is_callable($this, $method);

[sabina-talipova]

In ViewableData::__set() it should be is_callable([$this, $method]), not is_callable($this, $method);

Just using is_callable, probably doesn't solve the problem, even together with method_exist. I think problem is more deeper and will appear time to time, especially with some Field names.
How I understood, because we have a trait CustomMethods which has magic method __call and we use this trait in trait Extensible , that we use in class ViewableData .
It means if some class extends ViewableData or DataObject and we will have in ViewableData or DataObject classes setSomething methods and extending class has Something field, even if setSomething is private method_exist returns TRUE and is_callable returns TRUE, since CustomMethods has magic method __call .
I've done some tests and is_callable returns TRUE for setFieldValue in EditableCustomRule class.

[maxime-rainville]

There probably should be a unit test to cover this edge case.

Are we happy with the magic setter accessing protected method?

[sabina-talipova]

@emteknetnz said that we should check that method is NOT private. Public or protected are fine.

[sabina-talipova]

There probably should be a unit test to cover this edge case.

DONE. New test case was added.

[maxime-rainville]

LGTM